Oil change -- oil seems VERY dirty

[SeaHarlequin]

I recently changed my oil and had some questions about the dirty oil.

I use Shell Rotella 10W-30 diesel engine oil which is translucent and amber. It has been about 30 hours since the last oil change. The dirty oil is very black and opaque -- I can't even tell it is a synthetic oil.

I also think there's a faint smell of gasoline but I can't tell if it's coming from the dirty oil, the container it's in (it's a recycling container provided by the city and was not clean), or if I'm imaging things. Given the oil system flow schematic in the Moyer manual (5-3, figure 7), it doesn't look like there would be any interaction between the gasoline and oil but I've also read that Atomic 4 engines burn some oil so maybe I'm missing something and there is interaction between the two.

Is this normal, especially after 30 hours? If not, what are some diagnostic steps I should start looking into?

Should I be changing oil more frequently? The manual says every 50 hours but maybe certain conditions that my engine may be dealing with call for more frequent changes?

Is the color and opacity due to mechanical or chemical changes? Is the engine wear causing so much debris or is this due to reactions from heat, metals, etc, or something else entirely?

Thanks for any feedback or suggestions you can offer!

[roadnsky]

Do you have a MANUAL or ELECTRIC fuel pump?
Is this the first oil change that YOU have done on the engine?

[Dave Neptune]

SeaHarliquin, the oil should not be so contaminated after 30 hours. My first thought is that you did not get all of the old oil out, not at all uncommon. It can be a problem getting to the "bottom of the pan" and staying there. I always used a suction type through the dip-stick (late model) with a piece of 1/4" copper tubing so I could feel it "hit the bottom" of the pan.

I would not use a 10-30 of any kind in an A-4 unless I was in a very cold area. The clearances in these beasties needs a bit more viscosity to maintain good oil pressure, especially an old engine. Straight 30wt or 20-40 seem to work better for steady lubrication pressure.

RE the gas smell, be sure if you can. If you have the mechanical pump it is a sign the diaphragm is starting to leak and needs rebuilding. If you have an electric pump the engine could be way to "rich" running and some fuel is getting by the rings. How do the plugs look, sooty could be that indication.

Dave Neptune

[SeaHarlequin]

Thank you both for your replies.

I have an electric pump. I did do one oil change when I first bought the boat but had trouble getting oil out so that may be it. I recently bought a suction pump which lets me get oil out via the dipstick so that shouldn't be a problem going forward.

I'll change up the type of oil used and pull the spark plugs to check their conditions. Thanks!

[Dave Neptune]

SeaHarliquin, that is probably it then. I do suggest that you adapt a "1/4" copper tube. I used a piece of 1/4" I.D. tubing to adapt the copper to the tube supplied, held with a couple of hose clamps. If you have good feel you can bend ever so slightly to get to the lowest point I could find about 1/2~3/4" toward the trans not exactly straight down the "dip stick tube". Makes oil changes much easier and more thorough.

Dave Neptune

[edwardc]

Another good idea would be to add an aftermarket oil filter to the system. MMI does not sell one, but they are available from others, such as Indego. It has the added benefit that it provides a way to install an oil pumpout tee + shutoff valve on the oil return line which goes directly to the bottom of the crankcase. Makes oil changes a snap. No more fighting with a skinny tube thru the dipstick hole!


Excessive blowby could account for both the dirty oil and the gas smell in the oil. Many of us, myself included, have been using 15W40 with good results for years. The extra viscosity may help you. 15W40 also has the advantage of being the commonest oil for diesel engines, so it's widely available, unlike straight 30W which is becoming hard to find.

Without an oil filter, you might try reducing your change interval to 25 hrs. With the filter, I do mine every 50 hrs.

[Mo]

A 30 hour oil change is good practice as is your use of a diesel oil. I prefer 15W40 but whatever you feel good with. I've been using 15W40 since 2007...no mechanical issues.

The diesel oil does have lots of detergent in it as well, so if oil previously used were not of a high detergent level sludge could have build up and the use of the diesel oil started work on it...turning the oil dark. My first few oil changes were like that. I change mine at 25 hrs and at the end of that, after 13 yrs, it's clear and I have to look close to see the level.

[SeaHarlequin]

Another good idea would be to add an aftermarket oil filter to the system. MMI does not sell one, but they are available from others, such as Indego.

I did not know about that option, thank you -- I'll look it up!

Excessive blowby could account for both the dirty oil and the gas smell in the oil.

Could you please help me understand what excessive blowby is? I searched the forums/google and found these:

http://www.moyermarineforum.com/forums/showpost.php?p=5994&postcount=3

http://www.atomic4.com/faqcvs.htm

And this with a worrisome video in the first post:

http://www.moyermarineforum.com/forums/showthread.php?t=6408

So far, what I've read in those doesn't yet explain what's physically happening that causes excessive blowby. What "rings" and timing are they talking about?

A 30 hour oil change is good practice as is your use of a diesel oil.

15W40 also has the advantage of being the commonest oil for diesel engines, so it's widely available, unlike straight 30W which is becoming hard to find.

So it wasn't just my imagination I went to three stores before finding SAE 30. I'll take your and Mo's advice and replace the oil well before the 50 hour mark and look into 15W40.

Thanks for all the help!

[Dave Neptune]

SeaHarliquin, another point on the "blow-by" situation. Quite often especially in older engines the "blow-by" is often from to much advance in the timing. Once you get it running again try backing the timing off a tiny bit.

If it is the timing, you may notice that the engine actually runs smoother with less advance in the timing.

If you can post a pic of the plugs lined up in order so we can see the ceramic over the electrode.

Dave Neptune

[ronstory]

I use 15W-40 as well on my current engine. I've found that putting the MMO in crankcase I can get more 'gunk' out of the 40 year old oil pan.

When I'm going to change the oil on next trip to the boat, I dump a pint of MMO into the crankcase and let it warm up for 20-25mins at the slip. Then I close up the boat and head home.

In 2-3 weeks when I return, I let the engine warm up for again and then drain the oil using a suction device. Before I started adding the MMO, the oil was reasonably clean at 40 hours, still 'oil colored'. Now with the addition of MMO and letting it sit, the oil comes out pretty much black due to the extra solvents. The oil looks like it came from a diesel engine.

You could also dump in come ATF and get a similar result. However, I buy MMO in the gallon container and would rather not have to carry an extra fuild.

YMMV.

[SeaHarlequin]

Quite often especially in older engines the "blow-by" is often from to much advance in the timing. Once you get it running again try backing the timing off a tiny bit.

Thank you. I didn't consider that -- I have an electronic ignition and for some reason, I thought adjusting timing was not needed with EI as it would automatically take care of things. I'll read up on that.

If you can post a pic of the plugs lined up in order so we can see the ceramic over the electrode.

Sounds good, I'll try to get those pulled and photographed this weekend. Thanks!

[SeaHarlequin]

I've found that putting the MMO in crankcase I can get more 'gunk' out of the 40 year old oil pan.

When I'm going to change the oil on next trip to the boat, I dump a pint of MMO into the crankcase and let it warm up for 20-25mins at the slip. Then I close up the boat and head home.

In 2-3 weeks when I return, I let the engine warm up for again and then drain the oil using a suction device.

Thank you for that suggestion. To make sure I understand, I would just dump a pint of MMO directly into the main oil tube? Is there any harm in "overfilling" things -- if the engine oil dipstick already registers full, do I need to extract some oil before adding that quart?

You could also dump in come ATF and get a similar result.

Thanks!

[ronstory]

Over filling a pint is not a big deal if you are not using the engine under load. You may get some crank 'splash' but that's a good thing when you are trying remove deposits.

I've also dropped a full quart in and had no ill effects. But the key is not to use the engine for propulsion, just to warm up the oil and let is splash around and soak.

Edit: Yes, just dump it into the crankcase oil fill.

[SeaHarlequin]

If you can post a pic of the plugs lined up in order so we can see the ceramic over the electrode.

Here are the plugs in order with 1 being on the left and 4 being on the right.

I appreciate any input you can give by looking at these. Thanks!

[Dave Neptune]

Not bad

SeaHarliquin, the plugs look to be running rich which is probably in the carb. I say carb because if the "timing" is indeed to far advanced "some" of the black could be from oil. Usually if you have oil fouling the entire area around the electrode will be encrusted with carbon and oily soot which I don't see.

My first guess is that the "float" level is to high. The factory jetting is pretty close so if the jets are stock about all it can be is the float level. I have always found the A-4 really likes the float set a bit to the low side. This does add a few extra turns to the cold start scenario but yields a cleaner running engine.

Remember any updraft carburated engine like the A-4 should be a bit hard to start!!!!! And needing a bit of choke for warm re-start just means you are closer to a clean burning engine.

The ceramic portion of the electrode is the heat sink for the plug and you want to see a creamy chocolate sort of color. If the metal end and internal area of the plug look black as well as part of the "ground lug" is a bit black don't worry it's just an old engine running clean with a "tan" ceramic .

Dave Neptune